[DarkRanger]

Apologies if these are stupid questions, but there's a couple things I've been wondering that I haven't been able to find any information on.

First, are similar factions in different cities independent? For example, there's several temples of Kossuth and Cyric floating around, is each temple it's own unique faction? Where a player is limited to joining as a member of one temple per city? Or is someone who joins the temple of Kossuth in Bezantur also a member of the temple of Kossuth in Tyraturos?

Temples are definitely independent of each other, only certain legions have bases in more than one city

Similar questions for the Thieves' Guilds - there's one in Bezantur, Eltabbar, and now apparently in Tyraturos - are these all separate factions? Or some sort of overarching Thayan Thieves' Guild?

Same

I suppose we may as well answer it for the legions as well - I'm 99% sure that each legion is its own faction, but if someone else is wondering (or if I'm wrong) it's good to have it in here.

This is the exception, sort of. Priador legion can use any Priador barracks, etc. But no legion can use the barracks of a different legion.

Second, are there options for expanding an existing faction? For example, let's imagine that Alek Kelter decided to toss out everything about his character, suddenly become a serial killer, and manage to become an officer in the Tower of Swift Death. Could he then go on to say "Hey, we should expand our reach" and found a chapter of the guild in Moszabbar?

You can always set up a personal house and either leave it open or hand out keys, and call it an abbey, chapter house, barracks, or whatever you like. Not sure if "official" support is doable, but it's not really necessary either.

(This example is obviously ridiculous and is something that would never actually happen, but the general idea is what I want to know - how open are the DMs to NPC factions being expanded by players?)